Development of an Infrared Free Electron Laser for User Experiments

• Project/Area Number: 08454081
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 固体物性Ⅰ(光物性・半導体・誘電体)
• Research Institution: Osaka University
• Principal Investigator: ISOYAMA Goro Osaka University, ISRI-Sanken, Professor, 産業科学研究所, 教授 (80125989)
• Co-Investigator(Kenkyū-buntansha): KATO Ryukou Osaka University, ISRI-Sanken, Research Associate, 産業科学研究所, 助手 (20273708) ; OKUDA Syuichi Osaka University, ISRI-Sanken, Lecturer, 産業科学研究所, 講師 (00142175)
• Project Period (FY): 1996 – 1997
• Project Status: Completed (Fiscal Year 1997)
• Budget Amount: ¥7,600,000 (Direct Cost: ¥7,600,000); Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000); Fiscal Year 1996: ¥5,400,000 (Direct Cost: ¥5,400,000)
• Keywords: FEL / Infrared / Linac / Wiggler / Diffraction Loss / Gain

Research Abstract

We are modifying the free electron laser based on the L-band linac at the Institute of Scientific and Industrial Research, Osala University in order to develop an infrared free electron laser for user experiments. We have modified the free electron laser to expand the wavelength region, especially to the longer wavelength side, and have developed related technologies for it. We have remodeled the wiggler to make the magnet gap variable, which makes not only the wavelength continuously tunable but also operation at a large K-value possible. The bending magnets on the upstream and the downstream sides of the wiggler were remodeled and new vacuum chambers with larger verticalsizes were installed, so that the diffraction loss in the longer wavelength region is made smaller. We detected laser light with a Ge : Ga detector in the wavelength region longer than 50 mum. In order to derive the FEL gain and the loss from the time evolution of laser light, we measured the time resolution of the de tection system using coherent synchrotron radiation emitted by a single bunch beam from the linac. In FEL experiments, we used a special electron gun with a smaller cathode area. Recently the electron gun used in usual operation was replaced with a higher brightness electron gun thought the output current from the new gun is comparable to the old one. We have found that it is possible to conduct FEL experiments also with the new gun. As a result, we can carry out experiments even in a short machine time. We use a crystal quartz plate as a window for taking light out from the optical resonator in vacuum in the wavelength region longer than 50 mum. We have observed FEL oscillation at 136 mum using an electron beam of 15 MeV energy, which is the longest wavelength so far obtained with the FELs using RF linacs.
We are still modifying the FEL.The mirror folders for the optical resonator will be replaced, larger mirrors will be used, and a new evacuated optical path is being made. After these modifications are completed, we will conduct FEL experiments further longer wavelength region.

Research Products

• [Publications] S.Okuda: "Remodeling of the free electron laser with the L-bandlinac at Osaka University" Proc. of the 3rd Asian Symp. on Free Electron Lasers and 5th Symp. on FEL Applications, Hirakata, Japan. 31-38 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] S.Okuda: "Remodeling of the wiggler for thefree electron laser with the L-bandlinac at Osaka University" Proc. of the 18th International Free Electron Laser Conference, Rome. Italy. II-103-II-104 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] R.Kato: "Wavelength extension of the ISIR-FEL toward the longer wavelength region for user experiments" Proc. of the 11th Symp. on Accelerator Science and Technology, Hyogo, Japan. 121-123 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] S.Okuda et al.: "Remodeling of the free electron laser with the L-band linac at Osaka University" Proc.of the 3rd Asian Symp.on Free Electron Lasers and 5th Symp.on FEL Applications, Hirakata, Japan. 31-38 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] S.Okuda et al.: "Remodeling of the wiggler for the free electron laser with the L-band linac at Osaka University" Proc.of the 18th International Free Electron Laser Conference, Rome, Italy. II-103-II-104 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] R.Kato el al.: "Wavelength extension of the ISIR-FEL toward the longer wavelength region for user experiments" Proc.of the 11th Symp.on Accelerator Science and Technology, Hyougo, Japan. 121-123 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] S.Okuda: "Remodeling of the free electron laser with the L-band linac at Osaka University" Proc.of the 3rd Asian Symp.on Free Electron Lasers and 5th Symp.on FEL Applications,Hirakata,Japan. 31-38 (1997)
• [Publications] S.Okuda: "Remodeling of the wiggler for the free electron laser with the L-band linac at Osaka University" Proc.of the 18th International Free Electron Laser Conference,Rome.Italy. II-103-II-104 (1997)
• [Publications] R.Kato: "Wavelengthextension of the ISIR-FEL toward the longer wavelength region for user experiments" Proc.of the 11th Symp.on Accelerator Science and Technology,Hyogo,Japan. 121-123 (1997)
• [Publications] S.Okuda: "Measurement of characteristics of the infrared free electron laser with the L-band linear accelerator at Osaka University" Nuclear Instruments & Methods in Physics Research. A375. 329-331 (1996)